JP3135753B2 - Recording / reproducing method and apparatus using probe - Google Patents

Abstract

A recording and reproducing method writes information in the form of bits by the physical interaction between a probe and a recording medium opposed to the probe. The method includes a recording step of recording information by shifting a forming position of each bit by a predetermined shift amount in a horizontal direction of the recording medium in accordance with information, and a reproducing step of reproducing the information, based on the shift amount of each recorded bit in the horizontal direction of the recording medium. A recording and reproducing apparatus is so constructed as to perform the steps. <IMAGE>

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing method and a recording / reproducing apparatus using a probe for writing or reading information by a physical interaction between a probe having a tip at a tip and a recording medium facing the probe. .

[0002]

2. Description of the Related Art In recent years, a scanning tunneling microscope (hereinafter abbreviated as STM) capable of directly observing the electronic structure of surface atoms of a conductor has been developed [G. Binnig et al. Ph
ys. Rev .. Lett, 49, 57 (1982)],
High resolution measurement of real space images can be performed irrespective of single crystal or amorphous.

[0003] The STM utilizes the fact that a tunnel current flows when a voltage is applied between a metal tip and a conductive substance to approach a distance of about 1 nm. This current is very sensitive to changes in the distance between them. By scanning the probe so as to keep the tunnel current constant, it is possible to read various kinds of information on all electron clouds in the real space. At this time, the resolution in the in-plane direction is about 0.1 nm.

Therefore, if the principle of STM is applied, high-density recording / reproducing on the order of atoms (sub-nanometers) can be sufficiently performed. For example, JP-A-61-
In the recording / reproducing apparatus disclosed in Japanese Patent No. 80536,
Writing is performed by removing atomic particles adsorbed on the medium surface by an electron beam or the like, and data is reproduced by STM.

Further, a method has been proposed in which recording and reproduction are performed by STM using a material having a memory effect on the switching characteristics of voltage and current, for example, a thin film layer of a π-electron organic compound or chalcogen compound as a recording layer. (Japanese
JP-A-3-161552, JP-A-63-161553). According to this method, the recording bit size is set to 10
As nm, recording and reproduction with a large capacity of 1012 bit / cm ² is possible. Further, for the purpose of miniaturization, there has been proposed an apparatus in which a plurality of probes each having a probe are formed on a semiconductor substrate, and a recording medium opposed thereto is displaced and recorded (Japanese Patent Laid-Open No. 62-281138). JP-A-1-19
No. 6751). For example, by combining a multi-probe head in which 2500 probes are arranged in a 50 × 50 matrix on a 1 cm ² silicon chip and the above-described material having a memory effect, 400 Mbits per probe and a total recording capacity of 1 Tbit are obtained. Digital data can be recorded and reproduced.

In such a recording / reproducing apparatus, a signal is generally recorded as a bit on the surface of a recording medium, and this is detected as a level change of a tunnel current (in the case of STM) at the time of reproduction. For example, in the case of recording a binary signal, bits are arranged on a recording medium and recording is performed based on the presence or absence of the bits, while information is read out by a change in a tunnel current between a tip at the tip of the probe and the recording medium (Japanese Patent Laid-Open Publication No. 63-96756). Further, it has been proposed to perform analog signal recording of a tunnel current according to the magnitude of information writing by using a medium for selecting a charge of a molecular size and a magnetic domain according to recording data as a recording medium (Japanese Patent Application Laid-Open No. HEI 2 (1990) -209686). -210633 publication).

[0007]

However, when data is recorded in such a manner based on the presence or absence of a bit or a signal level difference and the presence or absence of a signal from a bit or the signal strength difference is detected, the data is reproduced as follows. There was such a problem.

(1) As described above, STM or AFM
(Atomic force microscope) has a high resolution of about angstrom in the height direction. Therefore, when using this to construct a recording / reproducing apparatus on the order of nm, a high resolution in the height direction is a detection signal for a so-called noise component such as a small defect on the recording medium or a minute undulation in the height direction. Caused a great change. For this reason, a recording medium used for recording / reproducing has been required to have flatness and uniformity at the atomic level, but it has been difficult to produce a recording medium that satisfies this requirement over a wide area. Therefore, a recording / reproducing method capable of performing recording / reproducing with a sufficient S / N ratio even if the flatness of the recording medium is slightly roughened has been demanded, but there has been almost no such proposal.

(2) When an attempt is made to record an analog signal by changing the modulation amount of recording information bits in accordance with the size of the write information, it is necessary to form the recording bit shape based on the recording information with good accuracy on the order of angstroms. was there. However, it has been extremely difficult to actually perform analog recording by changing the recording bit shape accurately and analogously on the order of angstroms.

(3) Normally, in a recording / reproducing method using the principle of the STM, servo is applied so that a tunnel current signal between a tip and a medium is kept constant. For this reason, for example, when performing binary recording, it is necessary to perform modulation so that the recording signal does not have a DC signal component, instead of recording the original signal as it is. Therefore, a modulation circuit having a complicated configuration and a demodulation circuit for reproducing the modulation circuit are required.

An object of the present invention is to enable recording / reproducing with a sufficient S / N ratio even for a noise component, and eliminate the need for constructing a modulation circuit and a demodulation circuit having a complicated structure, thereby enabling a probe and a recording medium to be connected. An object of the present invention is to provide a recording / reproducing method and apparatus using a probe capable of easily extracting horizontal and vertical position control signals.

[0012]

According to a recording / reproducing method using a probe according to the present invention, information is written and read as bits by physical interaction between a probe having a tip at a tip and a recording medium facing the probe. In a recording / reproducing method using a probe, during recording, bits are recorded as position information with respect to a reference position in a horizontal direction of a recording medium, and data reproduction is performed by detecting a positional shift amount of the bits recorded during reproduction. I do.

As position information with respect to the reference position in the horizontal direction, positional deviation information of the probe in the main scanning direction can be recorded and reproduced.

As the position information with respect to the reference position in the horizontal direction, position shift information in a direction orthogonal to the main scanning direction of the probe is recorded and reproduced.

Further, as the recording / reproducing information, binary data can be recorded / reproduced, and the recording / reproducing can be performed by shifting a bit recording position for recording according to the value of the binary data in a binary manner.

Alternatively, analog data may be recorded / reproduced as the recording / reproducing information, and recording / reproducing may be performed by shifting a bit recording position for recording according to the value of the analog data in an analog manner.

Further, the recording / reproducing method using the probe of the present invention uses a probe for writing and reading information as bits by physical interaction between a probe having a tip at the tip and a recording medium facing the probe. In the recording / reproducing method, at the time of recording, a reference bit which is a reference at the time of reproduction and a data bit corresponding to recording data are simultaneously recorded, and the data bit is recorded as a positional deviation amount of the recording medium relative to the reference bit in accordance with the recording data. Recording is performed on a medium, and data reproduction is performed by detecting a horizontal displacement amount of a data bit with respect to a reference data bit during reproduction.

A recording / reproducing apparatus using a probe according to the present invention is a recording / reproducing apparatus using a probe for writing and reading information as bits by physical interaction between a probe having a tip at a tip and a recording medium facing the probe. In the apparatus, a modulation signal generator for performing bit recording, a position control signal generator for shifting a bit recording position in a horizontal plane direction of a recording medium according to recording data, a horizontal position of a bit recorded during reproduction It is characterized by having at least a phase comparator for detecting a shift amount and reproducing data.

The recording / reproducing apparatus using the probe of the present invention uses a probe for writing and reading information as bits by physical interaction between a probe having a tip at the tip and a recording medium facing the probe. In a recording / reproducing apparatus, a modulation signal generator for performing bit recording, a phase modulator for performing timing generation for recording by shifting a recording position of a bit in a horizontal plane direction of a recording medium according to recording data, and a reproducing apparatus. It is characterized by having at least a phase comparator for detecting the amount of horizontal displacement of the data bit from the reference data bit and performing reproduction.

[0020]

According to the present invention, in a recording / reproducing system for forming continuous bits on a recording medium using a probe having a tip at a tip and a recording medium facing the tip, the bits are recorded at a reference position in accordance with recording information. The information is recorded as position information in the horizontal (XY) plane direction of the medium, and at the time of reproduction, information is reproduced by detecting the amount of positional deviation of a bit from a reference position.

According to the present invention, in recording / reproducing when information is written / read by physical interaction between a probe and a recording medium facing the probe, information is recorded with or without a bit or with a bit size / height. Instead of recording / reproducing the difference due to the difference between the bits, the bits are recorded as the presence or absence of a horizontal displacement of consecutive bits or "displacement amount", and this is detected at the time of reproduction. Generally, an STM or the like has a resolution of about sub-nm in the in-plane direction. Therefore, in a recording / reproducing method in which minute bits having a bit size of about 10 nm are arranged side by side, a bit position shift is recorded as in the present invention. The reproducing method is capable of detecting a signal with a high S / N ratio, and is less susceptible to irregularities of the recording medium. Also, since bits are recorded almost continuously irrespective of the content of the data to be recorded, there are advantages such as easy control of the probe height / horizontal direction during reproduction, and the principle of STM and AFM. This is a recording / reproducing format convenient for a recording / reproducing apparatus that uses.

[0022]

Next, embodiments of the present invention will be described with reference to the drawings.

[Embodiment 1] FIG. 1 is a diagram showing the configuration of a recording / reproducing apparatus having a conductive probe and a recording / reproducing format according to Embodiment 1 of the present invention.

In FIG. 1, 1 is a conductive probe, 2
Is a cylindrical piezoelectric element which is a fine movement driving mechanism for driving the probe 1, and 3 is a recording medium. The cylindrical piezoelectric element 2 accesses the recording medium 3 by a coarse driving mechanism such as a linear motor (not shown). Reference numeral 10 denotes an XY fine movement drive circuit that outputs an XY drive signal 15.

Usually, between the probe 1 and the recording medium 3,
The bias voltage 16 is applied by the bias circuit 4, and the voltage approaches a level at which a tunnel current or a field emission current flows. The tunnel current or the field emission current enters the Z servo circuit 6 after being voltage-converted by the current-voltage conversion circuit 5. The Z servo circuit 6 outputs a distance control signal 7 so that the tunnel current or the field emission current becomes constant,
The distance control signal 7 is applied to an electrode 19 that drives the cylindrical piezoelectric element 2 in the Z direction. The probe 1 was made by mechanically cutting and sharpening platinum.

As the recording medium 3, a material having a memory effect on the switching characteristics of voltage and current was used. For example, a gold epitaxial growth surface on a flat substrate such as glass or mica is used as a substrate electrode. And recording medium 3
A squarium-bis-6-octylazulene (hereinafter abbreviated as SOAZ) was used as the recording medium 3 by forming a two-layer monomolecular film on the substrate electrode by the Langmuir-Blodgett method.

The bit recording is performed as follows. Normally, a bias voltage 16 is applied between the probe 1 and the recording medium 3 by the bias circuit 4, and the voltage is approaching a level at which a tunnel current flows. In this state, the probe 1 is moved to a desired position on the recording medium 3, the bias voltage from the bias circuit 4 is modulated, and a voltage exceeding a threshold voltage causing an electric memory effect is applied between the probe 1 and the recording medium 3. Apply and record. Actually, a bias voltage of about 0.1 V is applied between the probe 1 and the recording medium 3 by the bias circuit 4,
It is kept close to the extent that a constant tunnel current (1 pA) flows. After moving the probe 1 to a desired position on the recording medium 3 in this state, the control circuit 8 modulates the bias circuit 4 with the bias modulation signal 11 and applies a pulse voltage of 6 V between the probe 1 and the recording medium 3. Then 10-10
A bit having a size of 10 nm in which a current of 0 pA flows was formed, and the state was maintained after application of the pulse voltage. Therefore, the bit in the low resistance state is made to correspond to "1" or "0", and the bit recording is performed separately from the recording area in the high resistance state. At the time of recording, the control circuit 8 controls the scanning signal 9
To drive the cylindrical piezoelectric element 2 via the XY fine movement drive circuit 10. Thus, the probe 1 performs bit recording corresponding to “0” and “1” along the main scanning (X) direction while performing two-dimensional XY raster scanning on the recording medium 3. Thereafter, the probe 1 was scanned on the recording medium 3 to detect the shift amount of each bit from the reference bit position, and reproduced as information of "0" to "1".

A specific recording / reproducing method and recording / reproducing format will be described with reference to FIGS. FIG. 2 is a timing chart for explaining the recording / reproducing method of the first embodiment. At the time of recording, data input 1
7 along with the data bit 201 which is a signal corresponding to
The clock bits 200 required for recording and reproduction are recorded. The recording area of the recording medium 3 is divided into a head area where a clock signal is recorded and a data area where recording data is written.
A clock bit 200 for reproducing recorded data is recorded in the preceding area, and a clock signal is extracted at the time of reproduction. In the data area, recording data is recorded as binary data, and bits corresponding to the information “0” and “1” at this time are arranged as shown in FIG. That is, the bit corresponding to the information “0” is recorded at the same position as the arrangement of the clock bits 200. On the other hand, the bit corresponding to the information "1" is printed while being shifted in the main scanning (X) direction from the position where the clock bit 200 should be (see FIG. 2).

A description will be given of the bit position shift recording at the time of recording. The clock bit 200 and the information “0” bit were generated by generating a bias modulation signal and applying a voltage to the recording medium when the probe approached the bit recording position in accordance with the timing from the control circuit 8. Bit diameter is about 1
Since it was 0 nm, clock bits and information "0" bits were formed at equal intervals of about 20 nm. On the other hand, when recording the recording signal “1”, the control circuit 8 generates an X modulation signal 12 for modulating the cylindrical piezoelectric element 2 in the X direction simultaneously with the bias modulation signal 11. Thereby, the probe tip position is shifted in the main scanning (X) direction. In this state, when the bias circuit 4 generates a recording voltage, the bits are recorded while being shifted from the position where the clock bit 200 should be in the main scanning direction. The cylindrical piezoelectric element 2 used in this embodiment is a PZT having an outer diameter of 7 mm, an inner diameter of 5 mm, and a height of 15 mm.
This is a cylindrical piezoelectric element. This piezoelectric element is divided into drive electrodes and can be driven in three-dimensional directions. When the displacement characteristics of the cylindrical piezoelectric element made of PZT were measured with a capacitance displacement meter, the displacement sensitivity in the XY directions was 10 nm / V. At this time, the control circuit 8 generated a modulation signal of 1 V as the XY modulation signal 12, and formed a bit by shifting the probe position by 10 nm in the main scanning direction when recording the recording signal "1".

The bit position shift amount was determined as follows. Bits are arranged and recorded at equal intervals on the recording medium 3 as check bits. Bits are recorded with a slight displacement depending on the shape of the probe tip. After recording, the bit string is scanned to check the horizontal variation in the bit recording position, and the bit position is shifted by an amount larger than the bit position variation during recording. In the present embodiment, since the positional variation of the recording bit was about 1 nm or less, the probe position was shifted by 10 nm in the main scanning direction when recording the recording signal "1".

When reproducing the bit recorded in this way, the phase of the current signal 13 was compared with the phase of the current signal 13 using the reproduction reference clock 202 stabilized based on the clock bit output of the preceding recording area. That is, when the phases of the clock output and the current signal are the same (the phase difference is “0”), the recording signal is “0”. On the other hand, if the clock output and the signal are out of phase, the recorded signal is “1”. In this way, reproduction was performed by comparing the phase of the clock output with the current signal, and a data output 18 was obtained.

FIG. 3 is a diagram showing a signal reproducing circuit used in FIG. This reproduction circuit is a part of the control circuit 8. In FIG. 3, the current signal 13 is connected to a phase locked loop (PLL3
06), and the signal was reproduced. That is, phase comparator 302, loop filter 303, amplifier 304, VC
A PLL 306 is formed by an O (voltage controlled oscillator) 305. At the time of reproduction, the phase information of the current signal is important.
For this reason, after the current signal output 13 is amplified by the amplifier 300, the amplitude is limited by the limiter 301 to obtain a signal having a constant amplitude. The output of the limiter 301 is input to the PLL 306. The PLL 306 is connected to the output of the limiter 301 and the VCO 30
5 is compared with the output. The PLL 306 changes the control voltage from the VCO 305 such that the phase difference between the two becomes minimum when the frequencies of the two inputs match. At this time, the VCO control voltage 307 for following becomes a reproduction signal. That is, the control voltage for following the bit is “0”.
Is detected as a change in the amount of voltage that causes a phase shift of 90 ° due to the difference between “1” and “1”. Therefore, this is binarized to obtain reproduction data 18 (see FIG. 2).

During reproduction, the control circuit 8 performs position control in the Y direction by synchronously detecting the current detected from the recording bits while slowly modulating the probe in the sub-scanning direction (Y direction). ing. This position control signal is the tracking signal 14. In this embodiment, the recording bits are recorded with their position modulated only in the main scanning direction, and the bits appear almost continuously. Therefore, the tracking signal 14 could be continuously taken out regardless of the content of the recording data, and the position of the probe 1 could be easily controlled.

If the output of the clock bit in the preceding recording area cannot be obtained stably, it is considered that the tip of the probe is deformed, the variation in the bit recording position is increased, and the clock bit is undulated and recorded. In this case, since the S / N at the time of recording / reproducing decreases, the tip of the probe is cleaned to perform recording / reproducing after obtaining the bit recording position reproducibility.

The recording method according to the present invention is not limited to the method in which the probe 1 performs two-dimensional XY raster scanning on the recording medium 3 as shown in this embodiment.
For example, move the probe circumferentially and spirally,
Recording while shifting the bit position in the circumferential track direction,
Reproduction may be performed.

In this embodiment, a recording / reproducing apparatus to which STM is applied has been described. However, the concept of the present invention is not limited to this. Can be applied to a recording / reproducing apparatus that records a change in the order of nm.

[Embodiment 2] FIG. 4 is a diagram showing the configuration of a recording / reproducing apparatus having a conductive probe and a recording / reproducing format according to Embodiment 2 of the present invention. The overall configuration is very similar to the first embodiment in FIG. 4, reference numeral 401 denotes a conductive probe, 402 denotes a cylindrical piezoelectric element which is a fine movement driving mechanism for driving the probe 401, and 403 denotes a recording medium. The cylindrical piezoelectric element 402 accesses the recording medium 403 by a coarse driving mechanism such as a linear motor (not shown). 408 is a scanning signal 409 and a tracking signal 41
The control circuit 421 outputs an XY drive signal 415.

Normally, a bias voltage 416 is applied between the probe 401 and the recording medium 403 by the bias circuit 404.
Is applied, and it approaches to the extent that a tunnel current or a field emission current flows. The tunnel current or the field emission current is converted into a voltage by the current-voltage conversion circuit 405 and then enters the Z servo circuit 406. Z servo circuit 40
6 outputs a distance control signal 407 so that the tunnel current or the field emission current becomes constant, and the distance control signal 407 is applied to an electrode 419 that drives the cylindrical piezoelectric element 402 in the Z direction. For the probe 401, platinum that was mechanically cut and sharpened was used.

As the recording medium 403, a material having a memory effect with respect to the switching characteristics of the voltage and current is used as in the first embodiment.

In the first embodiment, when performing the binary bit recording, the recording is performed while the probe position is shifted in the main scanning (X) direction by the XY driving signal of the XY fine movement driving circuit 10. In the present embodiment, the bias circuit is used. Recording voltage application timing control from 404 was performed, and printing was realized while shifting the bit arrangement in the main scanning direction. A specific recording method at this time will be described with reference to FIGS. FIG. 5A is a diagram showing a phase modulation circuit 503 in the control circuit 408 of FIG. 4 for performing phase modulation with binary information. FIG. 5B is a diagram for explaining a recording / reproducing method according to the second embodiment. It is a timing chart. A carrier wave having two phases shifted (carrier wave 420 in FIG. 4) is prepared, and "0" and "1" of binary data are converted into phase information of each carrier wave. 5A and 5B, two carriers 501 and 5
As 02, y = A · sin ωt... Carrier 501 y = A · sin (ωt−π / 2)... The frequencies of the carriers 501 and 502 are determined by the maximum spatial frequency at which bits can be recorded on the recording medium and the scanning speed of the probe tip. For example, when the bit size is 10 nm and the pitch is 2
Recording at 0 nm, probe speed 200 μm / sec
When scanning is performed by using the carrier waves 501 and 502, the frequency is 1
0 kHz. Then, the carrier waves 501 and 502 are input by “0” and “1” of the data input 417 which is binary recording data.
Are switched by the selection circuit 503 so as to select each of them. The phase modulation signal 50 output from the selection circuit 503
4 to control the timing of the bias circuit 404.
That is, the phase modulation signal 504 is converted into, for example, a binarization circuit 505.
To generate a bias modulation signal 411 which is a timing signal for generating a recording voltage. And the bias modulation signal 4
The recording was performed by modulating the bias voltage 416 by 11.

The reproducing circuit has the same configuration as that of FIG. That is, phase comparator, loop filter, amplifier, V
A PLL is formed by a CO (voltage controlled oscillator). The phase information of the reproduced signal is important. Therefore, the current signal 413
After the output was amplified, the amplitude was limited by a limiter to obtain a constant amplitude. This limiter output is put into the PLL. The PLL compares the phase with the output, and changes the output of the VCO so that the phase difference between the two becomes minimum when the frequencies match. At this time, the control voltage for phase tracking becomes a demodulated signal. In other words, the VCO control voltage for following appears as a voltage change that causes a phase shift of 90 ° due to the difference between the bits “0” and “1”. Therefore, binary data was reproduced by binarizing the control voltage signal, and a data output 418 was obtained.

In this embodiment, the binary data is modulated by two carrier waves having different phases and recorded as bits. However, the binary data may be modulated at two different frequencies and recorded as bits.

[Embodiment 3] FIG. 6 is a diagram showing the structure of a recording / reproducing apparatus having a conductive probe and a recording / reproducing format according to Embodiment 3 of the present invention. The overall configuration is very similar to the first embodiment in FIG. In FIG. 6, 601 is a conductive probe, 602 is a cylindrical piezoelectric element which is a fine movement driving mechanism for driving the probe 601, and 603 is a recording medium. The cylindrical piezoelectric element 602 accesses the recording medium 603 by a coarse driving mechanism such as a linear motor (not shown). Reference numeral 621 denotes an XY fine movement driving circuit that outputs an XY driving signal 615.

Normally, a bias voltage 616 is provided between the probe 601 and the recording medium 603 by the bias circuit 604.
Is applied, and it approaches to the extent that a tunnel current or a field emission current flows. The tunnel current or the field emission current enters the Z servo circuit 606 after being voltage-converted by the current-voltage conversion circuit 605. Z servo circuit 60
Reference numeral 6 outputs a distance control signal 607 so that the tunnel current or the field emission current becomes constant. The distance control signal 607 is applied to an electrode 619 for driving the cylindrical piezoelectric element 602 in the Z direction. The probe 601 was made by mechanically cutting platinum and sharpening it. Note that the bias voltage 61
6 is modulated by the bias modulation signal 611.

As the recording medium 603, a material having a memory effect with respect to the switching characteristics of the voltage and the current was used as in the first embodiment.

In the first embodiment, when printing is performed, the probe position is scanned in the main scanning direction (X) by the XY driving signal of the XY fine movement driving circuit 10.
The recording was performed while shifting in the direction. In this embodiment, the probe position is shifted in the direction (Y direction) orthogonal to the main scanning, and the analog recording of the data input 617 is performed. Analog reproduction is performed as the data output 618.

A description will be given of the bit position shift recording at the time of recording. FIG. 7 is a timing chart showing a bit layout according to the third embodiment. The bits consist of information bits that are analog recording information and have a positional shift amount in the sub-scanning (Y) direction from the clock bits 701 and 702 that are continuously arranged.

The control circuit 608 modulates the bias circuit 604 to record clock bits 701 at regular intervals while moving the probe in the main scanning (X) direction. Further, after recording the clock bit, Y
Bit recording is performed by shifting the direction probe position.

Since the bit diameter was actually about 10 nm, the clock bits 701 were formed at regular intervals of about 20 nm. On the other hand, when recording information bits, the control circuit
Generating a Y modulation signal 612 for modulating the Y fine movement driving device;
The bit recording was performed with the probe tip position shifted in the sub-scanning (Y direction).

The same P used in the present embodiment as in the first embodiment is used.
This is a ZT cylindrical piezoelectric element. Since this piezoelectric element had a displacement sensitivity of 10 nm / V in the X and Y directions, the modulation circuit generates a voltage of 2 V at maximum according to the analog amplitude of the recording signal and generates a displacement of 20 nm at maximum in the sub-scanning (Y) direction. I let it. In this manner, the main scanning was performed while forming a bit shifted in the sub-scanning direction from the clock bit position, and printing was performed.

Next, reproduction of recorded bits will be described. At the time of reproduction, the control circuit generated a scanning signal 609 so as to perform main scanning (X) while oscillating (wobbling) the probe with a width of about 30 nm in the sub-scanning (Y) direction, and reproduced information.

At this time, a reproduction clock is generated based on the signal from the clock bit. By comparing the phase of the reproduced clock with the phase of the wobbling signal, a position control (tracking) signal 614 in the Y direction was generated to perform horizontal position control. When tracking is applied, the probe 60
1 performs main scanning (X direction) along a clock bit string. When phase detection of the current signal 613 is performed with the reproduced clock signal in this state, a signal corresponding to the amount of displacement of the recording bit from the clock bit is obtained from the detector as a phase difference signal. This was reproduced as an analog data output 618.

Note that the bit layout of the bit position shift recording is not limited to the form shown in FIG. 7, and the probe is scanned in the main scanning (X) direction and in the sub scanning (Y) direction as shown in FIG. Two bits may be recorded in pairs. At this time, recording is performed while changing the bit interval of the bit pair in an analog manner. For example, when the bit diameter is 10 nm, bit recording is performed at a pitch of 20 nm in the main scanning direction.
At this time, the maximum bit interval is 2 depending on the value of the analog data.
Recording was performed while shifting by 0 nm. During reproduction, main scanning was performed while wobbling with a width of 40 nm in the sub-scanning direction, and a signal from a bit was detected. Since bits are formed at a pitch of 20 nm in the main scanning direction, the detection signal is demodulated and data is reproduced using a clock determined by the pitch and the scanning speed of the probe.

[0054]

According to the present invention, a recording / reproducing method for writing or reading information as bits by physical interaction between a probe having a tip at a tip and a recording medium facing the probe, and recording / reproducing using the same. The following effects can be obtained by detecting data position deviation of recorded bits and reproducing data in the device. (1) S / N sufficient for noise components such as small defects on the recording medium and minute undulations in the height direction
Recording / reproduction at a ratio becomes possible. (2) Without configuring a modulation circuit and a demodulation circuit having a complicated configuration,
Horizontal and vertical position control signals between the probe and the recording medium can be easily taken out, and stable reproduction of the recording signals can be achieved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a recording / reproducing apparatus having a conductive probe and a recording / reproducing format according to a first embodiment of the present invention.

FIG. 2 is a timing chart for explaining a recording and reproducing method according to the first embodiment.

FIG. 3 is a diagram showing a signal reproducing circuit used in FIG. 1;

FIG. 4 is a diagram showing a configuration of a recording / reproducing apparatus having a conductive probe and a recording / reproducing format according to a second embodiment of the present invention.

5A is a diagram showing a phase modulation circuit 503 in the control circuit 408 of FIG. 4 for performing phase modulation with binary information, and FIG. 5B is a diagram for explaining a recording / reproducing method according to the second embodiment. Timing chart.

FIG. 6 is a diagram showing a configuration of a recording / reproducing apparatus having a conductive probe and a recording / reproducing format according to a third embodiment of the present invention.

FIG. 7 is a timing chart showing a bit layout according to a third embodiment.

FIG. 8 is a timing chart showing another example of a bit layout according to the third embodiment.

[Explanation of symbols]

 Reference Signs List 1 probe 2 cylindrical piezoelectric element 3 recording medium 6 Z servo circuit 11 bias modulation signal 12 X modulation signal 13 current signal 14 tracking signal 17 data input 18 data output 300 amplifier 301 limiter 305 VCO 306 PLL 401 probe 402 probe cylindrical piezoelectric element 403 Recording medium 406 Z servo circuit 409 Scanning signal 411 Bias modulation signal 413 Current signal 414 Tracking signal 417 Data input 418 Data output 420 Carrier 501, 502 Carrier 503 Selection circuit 504 Phase modulation signal 505 Binarization circuit 601 Probe 602 Cylindrical piezoelectric element 603 Recording medium 606 Z servo circuit 609 Scanning signal 611 Bias modulation signal 612 Y modulation signal 613 Current signal 614 Tracking signal 617 Data input 18 Data output

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B 9/14

Claims (8)

(57) [Claims] 1. A recording / reproducing method using a probe for writing and reading information as bits by physical interaction between a probe having a tip at a tip and a recording medium facing the probe. A recording / reproducing method using a probe, characterized in that bits are recorded as position information with respect to a reference position in a direction, and data reproduction is performed by detecting a positional deviation amount of bits recorded during reproduction. 2. The recording / reproducing method using a probe according to claim 1, wherein information on positional deviation of the probe in the main scanning direction is recorded / reproduced as position information with respect to the reference position in the horizontal direction. 3. The recording / reproducing method using a probe according to claim 1, wherein positional deviation information in a direction orthogonal to a main scanning direction of the probe is recorded / reproduced as the positional information with respect to the reference position in the horizontal direction. . 4. The recording / reproducing method according to claim 1, wherein binary data is recorded / reproduced as the recording / reproducing information, and a bit recording position for recording is binary-shifted in accordance with a value of the binary data. Recording / reproducing method using a probe. 5. The recording / reproducing apparatus according to claim 1, wherein analog data is recorded / reproduced as the recording / reproducing information, and recording / reproducing is performed by shifting a bit recording position for recording according to the value of the analog data in an analog manner. A recording and reproducing method using a probe. 6. A recording / reproducing method using a probe for writing and reading information as bits by physical interaction between a probe having a tip at a tip and a recording medium facing the probe, comprising: The reference bit and the data bit corresponding to the recording data are recorded at the same time, and the data bit is recorded on the recording medium as a positional shift amount of the recording medium with respect to the reference bit in accordance with the recording data. A recording / reproducing method using a probe, wherein data reproduction is performed by detecting a horizontal displacement amount with respect to a reference data bit. 7. A modulation for performing bit recording in a recording / reproducing apparatus using a probe for writing and reading information as bits by physical interaction between a probe having a tip at a tip and a recording medium facing the probe. A signal generator, and a position control signal generator for shifting the recording position of the bit in the horizontal direction of the recording medium in accordance with the recording data, and detecting the horizontal displacement of the bit recorded during reproduction to reproduce the data. A recording / reproducing apparatus using a probe, comprising at least a phase comparator for performing the operation. 8. A modulation method for performing bit recording in a recording / reproducing apparatus using a probe for writing and reading information as bits by physical interaction between a probe having a tip at a tip and a recording medium facing the probe. A signal generator, and a phase modulator for generating a timing for recording by shifting the recording position of the bit in the horizontal plane direction of the recording medium according to the recording data, and a horizontal direction from the reference data bit of the data bit at the time of reproduction. A recording / reproducing apparatus using a probe, comprising at least a phase comparator for detecting and reproducing a position shift amount.